Toxicity Reduction Test to Assist in Predicting Land Treatability of Hazardous Organic Wastes

摘要

Migration of toxic organics contained in the water soluble fraction (WSF) of land applied hazardous wastes poses the most serious threat to ground-water resources. A toxicity reduction (TR) test system is being proposed that will serve to determine if, and to what extent, attenuation of WSF organic constituents will occur in a well-managed land treatment system. The test system employs reduction of acute toxicity exerted by WSF organics over time as the measurement criteria. Acute toxicity of the WSF for three loading rates is determined using a bacterial bioluminescence assay. Dose-response curves for each loading rate and subsequent time interval are compared with those of previous sample sets. The waste is predicted to be a candidate for land treatment if a significant reduction of acute toxicity exists during the experimental period at any of the loading rates tested. The maximum acceptable initial loading rate (MAIL) for waste application is predicted from these data. The predicted MAIL rate is the highest rate tested in which toxicity reduction for the waste-soil WSF progresses steadily during the experimental period with the Day-42 EC50 approaching 100 percent. The most extensive use of the procedure to date has involved evaluation of land treatability for oily wastes from different sources within a refinery; i.e., lagoon bottom sludge, API separator sludge, slop oil emulsion solids, and Dissolved Air Flotation unit skimmings. Results from these evaluation tests indicate the potential usefulness of the TR procedure as one of the initial tests conducted in a laboratory screening test sequence for predicting land treatability potential of organic hazardous wastes.